带式机镁质球团热工制度仿真及优化

Simulation and optimization of thermal engineering system for magnesium pellets of straight grate

镁质球团矿冶金性能好,是一种优质炼铁炉料,其生产最适宜的设备是带式焙烧机,但镁质球团对焙烧均匀性要求高。针对带式机生产镁质球团,采用Fluent工具对焙烧过程进行了模拟仿真,以获得均匀的温度场。建模考虑了碳酸镁的分解、氧化镁含量对磁铁矿氧化的影响,仿真结果通过链篦杯实验进行了验证,模型模拟的温度准确率大于90%。随后利用仿真模拟,获得了镁质球团生产的适宜热工条件,优化后料层上、中、下3层的最高温度分别为1 179、1 202和1 166℃,且温度高于1 000℃的保持时间分别为17.5、15.4和15.5 min,料层温差明显减少,3层球团的强度分别为3 630、3 422和3 296 N/个,料层平均强度为3 449 N/个,相比实验室管炉试验确定的热工制度,其球团强度更均匀且平均强度增加842 N/个。

Magnesia pellets are a high-quality ironmaking charge with good metallurgical properties. The most suitable equipment for their production is straight grate, but magnesium pellets have high requirements for roasting uniformity. For the production of magnesia pellets by straight grate, the Fluent tool was used to simulate the roasting process to obtain a uniform temperature field. The decomposition of magnesium carbonate and the effect of magnesium oxide on the oxidation of magnetite were considered in the model. The simulation results are verified by the grate cup experiment. The temperature accuracy of the model simulation is greater than 90%. Then, using simulation, suitable thermal conditions for the production of magnesia pellets were obtained. After optimization, the maximum temperatures of the upper, middle and lower layers of the material layer were 1 179, 1 202 and 1 166 ℃, respectively, and the holding time for temperature higher than 1 000 ℃ is 17.5, 15.4 and 15.5 minutes respectively, the temperature difference of the material layer is obviously reduced, the strength of three-layer pellets is 3 630 N/piece, 3 422 N/piece and 3 296 N/piece, respectively, the average strength of the material layer is 3 449 N/piece. Compared with the thermal system determined by the laboratory tube furnace test, the pellet strength is more uniform and the average strength increases by 842 N/piece.